In March 1905, Janusz Korczak received his doctor's diploma and started working at the Children's Hospital in Warsaw. During 7 years of work in the hospital, Korczak served children as a doctor, teacher and writer. He persistently popularized pediatric knowledge.

In 1912, Korczak left the hospital and became the director of the Orphans' Home, under the care of the "Aid for Orphans" Society. He worked with Stefania Wilczyńska and they took care of 85 pupils. For Korczak, the Orphanage became a place of pedagogical observations of the educational process, and a place where new pedagogical ideas were born (for example, the paper "Tygodnik Orphanage" which was co-created by children).

On August 6, 1942, the Nazi German occupiers took Janusz Korczak, all co-workers and two hundred pupils out of the Orphans' Home to their last path. Janusz Korczak probably died in transport to Treblinka, and not in its gas chambers. "The poor health of Korczak could have made him unable to endure the hardships of the journey", PAP Prof. Jacek Leociak from the Center for Research on the Extermination of Jews of the Polish Academy of Sciences says.